bevel doesn't work right
if you press n and go to:
item -&gt; transform -&gt; scale
can you see if the scale is all 1?
for example scale is all 1

if it is not all 1, for example, if it is something like (4, 1, 0), it is not all 1

if this is the case, this might help: go into object mode, select the object that is causing the error, Press ctrl+A, and then choose Scale

now check to see if the scale is now is all 1. If it is try beveling again.
I hope this helps
if it does not work. Do you happen to have other modifiers or connections to other objects that might be changing the scale of the object?